JP6107742B2 - Heat treatment apparatus, heat treatment method and storage medium - Google Patents

Description

  The present invention relates to a technique for heating a substrate.

  In a device manufacturing process using photolithography, a heat treatment apparatus for heating a substrate coated with a resist solution or a substrate after exposure is used. Some heat treatment apparatuses heat a substrate by placing the substrate on a heating plate adjusted to a heating temperature.

On the other hand, there are various types of substrates used for manufacturing devices, and a substrate material (eg, tantalum) having a lower thermal conductivity than a silicon substrate (about 160 W / (m · ° C.)) generally used for manufacturing semiconductor devices. Lithium oxide (LiTaO ₃ ): about 4.6 to 8.8 W / (m · ° C.), gallium arsenide (GaAs): about 55 W / (m · ° C.), lithium niobate (LiNbO ₃ ): about 38 W / (m A process of heating the substrate made of (C) or the like) may be performed.

  However, when the substrate is heated by being placed on a heating plate, it is difficult to uniformly heat the entire surface of the substrate having a low thermal conductivity. For this reason, temperature unevenness occurs in the substrate surface, and the substrate is deformed and warped due to the difference in expansion coefficient between regions having different temperatures, making uniform heating more difficult. Further, when the substrate is deformed on the heating plate, the substrate and the heating plate come into contact with each other, which may cause a crack. In particular, the problem of warping when the substrate is heated has become larger as the substrate becomes larger and thinner. Furthermore, as described in Patent Document 1, some of the above-described substrates have a crystal structure having a different coefficient of thermal expansion depending on the orientation. When this type of substrate is exposed to a thermal change, the substrate may be broken due to the effects of stress strain generated inside the substrate.

  Here, in Patent Document 2, in order to densify a SOG (Spin On Glass) film formed by applying a coating solution for forming a silica-based film on a rotating semiconductor wafer, lift pins supporting a substrate are sequentially formed. A substrate heat treatment apparatus is described in which the temperature from the upper surface of the hot plate is lowered to change the heat treatment temperature of the substrate stepwise. However, Patent Document 1 does not describe a technique for performing uniform heating while suppressing the influence of warping when placed on a hot plate and heated.

JP 2008-301066 A: Paragraph 0004 JP-A-11-97324: paragraphs 0025 to 0026, FIG.

  The present invention has been made under such circumstances, and an object of the present invention is to provide a heat treatment apparatus, a heat treatment method, and this method capable of uniformly and quickly heating a substrate in which warpage occurs during a temperature rising process. Is to provide a storage medium storing the.

The heat treatment apparatus of the present invention is a heat treatment apparatus for heating a substrate.
A substrate that warps in the process of temperature rise and then returns to a flat surface is placed, a heating plate that is adjusted to a heating temperature that heats the substrate, and a projection that can be protruded from the heating plate. A support member for supporting from the lower surface side;
An elevating mechanism that is set on the upper side of the heating plate and moves the support member up and down between a delivery position where the substrate is delivered to the support member and a position on the lower side of the heating plate;
During the period in which the substrate is lowered from the delivery position, the substrate is heated up to a temperature at which warpage occurs due to the heat from the heating plate above the heating plate, and then the return time until the substrate returns to flatness is reached. And a controller that controls the position of the support member by operating the lifting mechanism to place the substrate on the heating plate after the passage.

The heat treatment apparatus may have the following configuration.
(A) The control unit stops the lowering of the support member at a first height position where the substrate is heated to a temperature equal to or higher than the temperature at which the warpage occurs, and the substrate to be processed is warped. The elevating mechanism is controlled to lower the support member again after the return time has elapsed. The first height position is set to a position where the distance from the heating plate is larger than the maximum displacement in the height direction of the warp generated in the substrate at the position. Further, the control unit stops the lowering of the support member at a second height position above the first height position, preheats the substrate to be processed, and then again supports the support member. Controlling the elevating mechanism to lower the position.
(B) The control unit obtains a timing at which the return time for the substrate to be processed elapses based on a correspondence relationship between the return time and the temperature at which the substrate warps, which is acquired in advance for each type of substrate. To estimate. Further, the control unit obtains a substrate to be processed based on a relationship between a distance from the heating plate adjusted to the heating temperature to the substrate, which is acquired in advance for each type of substrate, and a change in temperature of the substrate over time. To estimate the temperature and use it for position control when lowering the support member.
(C) A period until the control unit raises the substrate from the placement surface after placing the substrate on the placement surface of the heating plate after passing the substrate to the support member at the delivery position. The position and timing for raising and lowering the support member are determined on the basis of a heating sequence set so that the time integral value of the temperature of the substrate inside becomes a preset value. The time integral value of the temperature of the substrate is obtained based on the relationship between the distance from the heating plate to the substrate and the average temperature increase rate of the substrate, which are acquired in advance for each type of substrate.
(D) The substrate is made of a substrate material selected from a substrate material group consisting of lithium tantalate, gallium arsenide, and lithium niobate. Alternatively, the substrate is made of a substrate material having a thermal conductivity of 55 W / (m · ° C.) or less.

  In the present invention, after the substrate supported by the support member is heated above the heating plate and heated to a temperature at which the substrate is warped, a return time after the warped substrate returns to flatness has elapsed. Since the substrate is placed on the heating plate, uniform and rapid heating can be performed on the flat substrate.

It is a disassembled perspective view of the heat processing module which concerns on embodiment of this invention. It is a block diagram which shows the electric constitution of the said heat processing module. It is explanatory drawing which shows the relationship between the heating temperature of an evaluation board | substrate, and the time-dependent change of the curvature amount. It is explanatory drawing which shows the relationship between the heating temperature of another kind of evaluation board | substrate, and the time-dependent change of curvature amount. It is explanatory drawing which shows the structural example of curvature data. It is explanatory drawing which shows the relationship between the gap height from a heating plate, and the temperature rising characteristic of a board | substrate. It is explanatory drawing which shows the creation example of the heating sequence of a board | substrate. It is explanatory drawing which shows the conventional heating sequence. It is explanatory drawing which shows the calculation method of the heat history in the heating sequence of this example. It is a flowchart of the operation | movement which produces the said heating sequence. It is 1st operation | movement explanatory drawing of the said heat processing module. It is 2nd operation | movement explanatory drawing of the said heat processing module. It is 3rd operation | movement explanatory drawing of the said heat processing module. It is 4th operation | movement explanatory drawing of the said heat processing module. It is a schematic diagram which shows the state of the board | substrate processed with the said heat processing module.

  As an embodiment of the present invention, an example in the case of processing a lithium tantalate thin substrate (hereinafter referred to as “substrate W”) will be described. 1 and 2 show a configuration of a heat treatment module (heat treatment apparatus) 1 for heating the substrate W. FIG. For example, the heat treatment module 1 is mounted on a coating and developing apparatus that applies a resist solution to the substrate W to form a resist film, and develops the resist film after exposure.

As shown in the exploded perspective view of FIG. 1, the heat treatment module 1 of this example is provided on the upper surface of the base 11, and a heating plate 2 on which a substrate W to be processed is placed, and a substrate W on the heating plate 2. And a support pin 3 for mounting the.
The heating plate 2 has a structure in which a resistance heating element 21 is embedded in a disc-shaped heating plate made of ceramics such as SiC or AlN, and the resistance heating element 21 is connected to a power supply unit 23 ( Figure 2). A plurality of gap pins 22 that support the substrate W from the back surface are provided on the upper surface of the heating plate 2 at a height of 0.2 mm above the upper surface.

  The gap pins 22 are made of, for example, a ceramic columnar member having a diameter of 3 mm. One gap pin 22 surrounds the central position of the substrate W, and three gap pins 22 are spaced apart from each other along the circumferential direction of the heating plate 2. Is provided. The upper surfaces of these gap pins 22 correspond to the mounting surface of the substrate W in the heating plate 2, for example, a substrate W having a diameter of 200 mm is mounted.

  The support pin 3 has a structure in which a ceramic chip such as SiC is provided on an upper portion of a metal rod-shaped member such as stainless steel, and is configured as a rod-shaped member having a diameter of 1 mm as a whole. In the heat treatment module 1 of this example, three support pins (support members) 3 are arranged at intervals in the circumferential direction of the heating plate 2 so that each support pin 3 penetrates the heating plate 2 in the vertical direction. Is provided. The heating plate 2 is provided with a through hole 25 having a diameter of, for example, 3 mm for allowing the support pins 3 to pass therethrough.

  As schematically shown in FIG. 2, the lower end portions of these support pins 3 are connected to a common lifting member 31, and this lifting member 31 is connected to a lifting motor 32 disposed on the side of the base portion 11. ing. By elevating the elevating member 31 by the elevating motor 32, the support pins 3 can be protruded and submerged from the upper surface of the heating plate 2 while aligning the height positions of the upper ends of the three support pins 3. The substrate W is supported from the back side by the tip portions of these three support pins 3. The elevating motor 32 is stored in a box 17 disposed on the side of the base 11, for example.

  When the above-described elevating member 31 is raised and lowered, the tip of the support pin 3 is provided above the heating plate 2, and an external substrate transport mechanism (for example, a coating / developing apparatus provided with the heat treatment module 1). It moves between a transfer position where the substrate W is transferred to and from the position below the heating plate 2. In this example, the delivery position is installed, for example, at a position 16.5 mm above the upper surface of the heating plate 2.

The lifting motor 32 can stop the tip of the support pin 3 at an arbitrary position between the delivery position and a position on the lower side of the heating plate 2. As a result, the support pins 3 that support the substrate W can freely adjust the distance from the upper surface of the heating plate 2 to the substrate W.
The lifting member 31 and the lifting motor 32 correspond to a lifting mechanism for the support pin 3.

  Here, when the gap pin 22, the support pin 3, and the through-hole 25 are provided in the heating plate 2, the structure of the upper surface of the heating plate 2 becomes non-uniform, and the factor that hinders uniform heating in the plane of the substrate W It becomes. In this respect, in this example, the gap pin 22, the support pin 3, and the through hole 25 are made relatively small (the gap pin 22 has a diameter of 3 mm, the support pin 3 has a diameter of 1 mm, and the through hole 25 has a diameter of 3 mm). A decrease in in-plane uniformity when heating W is suppressed.

  Further, as shown in FIG. 1, a disk-shaped substrate guide 24 for preventing the displacement of the substrate W is provided in the circumferential direction of the substrate W around the mounting region of the substrate W on the upper surface of the heating plate 2. A plurality are provided at intervals. In the drawings other than FIG. 1, the description of the substrate guide 24 is omitted.

  Around the heating plate 2 described above, a cylindrical wall portion 12 that surrounds a space in which the substrate W is heated from the side is provided. As shown in FIG. 1, the cylindrical wall portion 12 is made of a flat cylindrical member made of metal, for example, and is placed on the substrate W supported by the support pins 3 or the heating plate 2. Is disposed so as to surround the substrate W from the side.

  As shown in FIG. 2, the lower end portion of the cylindrical wall portion 12 is connected to an elevating member 121, and this elevating member 121 is connected to an elevating motor 122 disposed on the side of the base portion 11. The cylindrical wall portion 12 is connected to the base portion 11 via the ring-shaped opening 111 (see FIG. 1) provided on the upper surface of the base portion 11 by moving the lifting member 121 up and down by the lift motor 122. It moves up and down between the position on the lower side and the position surrounding the substrate W on the support pins 3 and the heating plate 2 (see FIGS. 11 to 14).

  In this example, as described above, the elevating motor 32 for elevating the support pin 3 and the elevating motor 122 for elevating the cylindrical wall portion 12 are housed in the common box 17 (FIG. 1). For convenience, FIG. 2 shows the lift motor 32 and the lift motor 122 separated from each other.

  When the cylindrical wall portion 12 is raised, the upper end portion of the cylindrical wall portion 12 reaches above the delivery position of the support pin 3 and is supported by the support pin 3 so that the delivery position and the heating plate 2 are mounted. The entire movement area of the substrate W transported between the mounting surfaces is surrounded.

  Further, as shown in FIGS. 1 and 2, on the upper side of the cylindrical wall portion 12 raised to a position surrounding the moving region of the substrate W, a lid portion 13 is formed so as to close the opening on the upper surface side of the cylindrical wall portion 12. Is provided. The lid portion 13 is made of, for example, a metal disk-shaped member, and an exhaust pipe 16 for exhausting the inside of the processing space surrounded by the cylindrical wall portion 12, the lid portion 13, and the base portion 11 on the upper surface thereof. Is connected. The end of the exhaust pipe 16 is connected to an exhaust mechanism (not shown), and the substrate W can be heated while exhausting the processing space.

As shown in FIG. 1, the lid portion 13 has two end portions facing each other across the center portion by two cross beams 15 arranged so as to extend along the long side direction of the base portion 11. Is retained. Each cross beam portion 15 is supported by two support column portions 14 arranged to extend upward from the upper surface of the base portion 11, whereby the lid portion 13 faces the lower surface thereof to the heating plate 2. In this state, it is arranged above the heating plate 2.
In the drawings other than FIG. 1, the exhaust pipe 16, the cross beam portion 15, and the support column portion 14 are not shown.

  The base 11, the box 17, the cylindrical wall 12, the lid 13, and the like having the above-described configuration are stored in a housing (not shown). For example, a resist solution coating module or a development module of a coating or developing apparatus is used. Located adjacent to the installation area.

  Further, as shown in FIG. 2, the heat treatment module 1 is connected to the control unit 4. The control unit 4 includes a computer including a CPU 41 and a memory (storage unit) 42. The memory 42 heats the substrate W transferred to the support pins 3 by being transferred to the operation of the heat treatment module 1, that is, the heat treatment module 1. A program in which a group of steps (commands) related to control until the support pins 3 are raised again and transported to the delivery position and the processed substrate W is unloaded after being placed on the plate 2 and heated. Is recorded. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.

For example, the control unit of the heat treatment module 1 is shared with a control computer that controls the coating and developing apparatus on which the heat treatment module 1 is mounted.
Further, as shown in FIG. 2, the heat treatment module 1 is provided with an interface unit 5 including a touch panel type display for accepting input of substrate information and processing conditions described later from an operator and reporting an error. It has been.

Furthermore, the heat treatment module 1 of this example has a function of suppressing the occurrence of uneven heating due to the occurrence of warpage in the process of raising the temperature of the substrate W and heating the entire surface of the substrate W uniformly.
The detailed contents of the function will be described below with reference to FIGS.

The inventors have examined the warping phenomenon that occurs when the substrate W is heated by changing the heating temperature, the thickness of the substrate W, and the like. As a result, (1) there is a heating temperature at which warpage occurs in the substrate W and a heating temperature at which no warpage occurs, and (2) even when the substrate W is heated at a heating temperature at which warpage occurs. It has been newly found that the warpage is eliminated with the passage of time and the substrate returns to the flat substrate W.
3 and 4 described below, a thin substrate of lithium tantalate is used as the evaluation substrate.

The results of the preliminary experiments shown in FIGS. 3A to 3C and FIGS. 4A to 4C are obtained after placing the evaluation substrate on the heating plate 2 set to have a predetermined heating temperature. The change with time of the detected height of the upper surface of the evaluation board is shown. FIGS. 3A to 3C show the results of heating the evaluation substrate having a thickness of 200 μm on which the resist film or the like is not applied by changing the temperature of the heating plate 2 in various ways, and FIGS. Similarly, (c) shows the result of heating an evaluation substrate having a thickness of 400 μm.
As the height position, the height of the detection position set at a position closer to the center by 2 mm from the peripheral edge on the upper surface side of the evaluation substrate was detected by a laser displacement meter. In each figure, the horizontal axis indicates the elapsed time (seconds), and the vertical axis indicates the detection height (mm).

According to the experimental results of the evaluation substrate having a thickness of 200 μm shown in FIGS. 3A to 3C, when the set temperature of the heating plate 2 is 50 ° C., almost no warpage of the evaluation substrate was detected ( FIG. 3 (a)).
On the other hand, when the set temperature of the heating plate 2 was raised to 60 ° C., a warp of about 1.0 mm at maximum occurred as shown in FIG. When heating was continued as it was, the warpage gradually decreased, and the evaluation substrate returned to a substantially flat state about 10 seconds after the warpage was detected.

  Further, as shown in FIG. 3C, when the set temperature of the heating plate 2 is set to 110 ° C., the maximum value of the warp (about 1.7 mm), the time from when the evaluation substrate starts to warp until it returns flat ( In all cases (about 40 seconds), the temperature was higher than when the set temperature was 60 ° C.

  As described above, even if the evaluation substrates have the same thickness, if the set temperature of the heating plate 2 is different, warpage may or may not occur (hereinafter, the temperature at which warpage occurs is referred to as “warp start temperature”. )), And even when warping occurs, the maximum value of warping (hereinafter referred to as “warping amount”) and the time from the start of warping until it returns to flatness (hereinafter referred to as “return time”) are also different. Was confirmed.

Next, when the thickness of the evaluation substrate was 400 μm, even when the set temperature of the heating plate 2 was set to 80 ° C., almost no warpage was detected (FIG. 4A).
On the other hand, when the set temperature of the heating plate 2 is increased to 90 ° C., the warpage of the evaluation substrate is detected as shown in FIG. 4B, and therefore when the set temperature of the heating plate 2 is changed in increments of 10 ° C. ( Hereinafter, it is understood that the warping start temperature of the same in the present embodiment is 90 ° C. Further, the warping amount at this time was about 0.7 mm, and the return time was about 30 seconds. Furthermore, when the set temperature of the heating plate 2 was 110 ° C., the warpage amount was about 0.9 mm and the return time was about 46 seconds as shown in FIG.

  Thus, it was confirmed that the warp start temperature changes if the thickness of the evaluation substrate (type of substrate W) is different. Further, even when the set temperature of the heating plate 2 is the same, it has been confirmed that when the thickness of the substrate W is different, the values of the warpage amount and the return time are also different.

  As confirmed above, the substrate W in which the warpage has occurred returns to a flat state after the elapse of the return time. Therefore, if the substrate W is warped in advance and placed on the heating plate 2 after the return time has elapsed, the flat substrate W can be uniformly heated.

  In this regard, the temperature of the substrate W supported by the support pins 3 on the upper side of the heating plate 2 rises due to the influence of radiant heat from the heating plate 2 and the like. Therefore, the heat treatment module 1 of the present embodiment can cause the substrate W to warp while being supported by the support pins 3 by appropriately adjusting the height position at which the support pins 3 support the substrate W. it can. Further, by placing the substrate W on the heating plate 2 after the return time has elapsed, the substrate W that has returned to a flat surface can be heated on the heating plate 2.

  Regarding these functions, as shown in FIG. 2, the heat treatment module 1 previously uses the type of the substrate W (for example, the thickness dimension, the presence / absence of a coating film such as a resist film, the thickness dimension of the coating film, and the substrate material) as parameters. Warpage data 431 includes information on the warpage amount and return time with respect to the set temperature of the heating plate 2 (when the substrate W is placed on the heating plate 2, it can be regarded as the heating temperature of the substrate W after a sufficient time has elapsed). Remember as.

For example, as shown in FIGS. 5A and 5B, the warpage data 431 is stored as a table in which the amount of warpage and the return time are associated with the heating temperature of the substrate W (in FIG. 5). The warp data 431 relating to the above-described evaluation board is shown). According to the example shown in FIG. 5, when the heating temperature of the substrate W is viewed in order from the lowest, the temperature at which the warpage amount is not zero corresponds to the warp start temperature of the substrate W.
Note that the return time set in the warpage data 431 is a value (with a margin) with respect to the actually measured return time (see FIGS. 4B, 4C, 4B, and 4C). For example, a value obtained by increasing the measurement result by 10%, a value obtained by uniformly increasing the return time by 5 seconds, or the like may be used.

  Further, as shown in FIG. 2, the distance from the upper surface of the heating plate 2 to the lower surface of the substrate W when the height position at which the substrate W is supported by the support pins 3 is variously changed in the memory 43 of the heat treatment module 1. Corresponding to (hereinafter referred to as “gap height”), the temperature change of the substrate W with respect to room temperature (23 ° C.) is stored (temperature rise characteristic data 432).

  A plurality of sets of the temperature rise characteristic data 432 are stored using the type of the substrate W and the set temperature of the heating plate 2 as parameters. FIG. 6 is a temperature rise curve showing the temperature rise characteristic data 432 of the substrate W having a thickness of 200 μm when the set temperature of the heating plate 2 is 110 ° C. for each gap height (the gap height is, for example, 1. (It is created in increments of 0 mm, part of which is shown in FIG. 6). The gradient (temperature increase rate) of the temperature increase curve during the period in which the temperature of the substrate W is increasing decreases as the gap height increases. That is, the larger the gap height, the longer it takes to heat the substrate W.

  Further, the substrate W supported by the support pins 3 has a lower ultimate temperature as the gap height increases. Therefore, even if the substrate W is disposed at the gap height position where the ultimate temperature is lower than the warp start temperature, the substrate W does not warp. For this reason, when the substrate W is subsequently placed on the heating plate 2, the heating plate 2 is warped.

The heat treatment module 1 according to the present embodiment is based on the warpage data 431 and the temperature rise characteristic data 432, and the condition that warpage occurs before the substrate W is placed on the heating plate 2 and the return time elapses. In order to satisfy the above, a sequence is created in which the substrate W supported by the support pins 3 is heated while being lowered.
Hereinafter, a method for creating the heating sequence will be described. In the following description, it is assumed that the raising / lowering operation of the substrate W supported by the support pins 3 can be performed sufficiently faster than the temperature increase rate of the substrate W.

  As described above, in the heat treatment module 1 of this example, the substrate W supported by the support pins 3 at the delivery position is lowered to a certain gap height position to generate warpage. However, even when the substrate W is not placed directly on the heating plate 2 and heating is started above the heating plate 2, the substrate W is cracked due to a rapid temperature change. It may occur.

  Therefore, the heat treatment module 1 of the present example has a position above the position (second height position) before moving the substrate W to the gap height position (first height position) that causes warpage. Preheat at. In this preliminary heating, the substrate W may or may not be warped.

As described above, the heat treatment module 1 includes a stage for performing preliminary heating (hereinafter referred to as “first stage”), a stage for generating warpage of the substrate W (hereinafter referred to as “second stage”), and a heating plate 2. The substrate W is heated at three kinds of gap height positions including the stage of placing the substrate W on the substrate (hereinafter referred to as “third stage”).
The preheating temperature in this example is set to 60 ° C., for example. The heating stage number data 422 (three stages) and the preheating temperature data 421 (60 ° C.) are stored in the memory 42 of the control unit 4 in advance (FIG. 2).

FIG. 7 shows an example of the change over time of the temperature of the substrate W in the heating sequence in which the substrate W having a thickness of 200 μm is placed on the heating plate 2 set to 110 ° C.
In the example shown in FIG. 7, the room-temperature substrate W delivered to the support pins 3 at the delivery position (gap height 16.5 mm) is transported to a predetermined gap height position in the first stage and preheated. The temperature is raised to a temperature (60 ° C., which is also a warp start temperature according to FIG. 5A). After that, it is further conveyed to the gap height position on the lower side, and the temperature is raised to a temperature (80 ° C.) higher than the warp start temperature in the second stage. In this second stage, waiting for the return time of the warped substrate W to elapse is performed, and then, in the third stage, the substrate W is placed on the heating plate 2 and heated to 110 ° C.

On the other hand, referring to the temperature rise curve shown in FIG. 6, the ultimate temperature of the substrate W is a preheating temperature (60 ° C.) or a temperature at which warpage occurs (temperature equal to or higher than the warp start temperature (60 ° C.)). There are many combinations of gap height positions. For this reason, the position where preheating is performed, the position where the substrate W is warped, and the heating time of the substrate W on each of the heating plates 2 (heating times A, B, C (seconds) shown in FIG. 7) are also various. Can take any value.
Therefore, the heat treatment module 1 of this example determines the gap height position and the heating time at each stage based on the policy described below.

  FIG. 8 shows the change of the temperature of the substrate W over time in the conventional method in which the substrate W is immediately placed on the heating plate 2 and heating starts after the substrate W is delivered to the support pins 3 at the delivery position. Show. According to the conventional method, the substrate W transferred at room temperature is rapidly heated to the temperature of the heating plate 2 (T3 = 110 ° C.), and heating is continued for a predetermined time in this state.

  Compared with the change with time of the diameter of the substrate W in the conventional method, the change with time of the temperature of the substrate W shown in FIG. 7 gradually increases as the gap height changes. It is different in point. As described above, even if the temperature change of the temperature of the substrate W is different from the conventional method, the processing result of the substrate W (for example, in the case of the resist film baking process, the residual amount of the solvent in the resist film, etc.) Need to be approximately the same.

  In this regard, the inventors found that the time integral value of the temperature of the substrate W (hereinafter referred to as “thermal history”) during the period filled in with diagonal lines in FIG. If it is the same as the thermal history in the third stage), it is understood that the processing results of the substrate W in both heating methods are almost the same.

  Therefore, as shown in FIG. 2, in the heat history setting data 433 of the heat treatment module 1 of this example, the heat history of the conventional method shown in FIG. 8 is stored in advance as the heat history setting data 433 for each type of substrate W. ing. Then, the gap height position and the heating time at each stage are determined so that a heat history substantially matching the heat history setting data 433 corresponding to the type of the selected substrate W is realized.

  The thermal history of the first stage to the third stage is obtained, for example, by linearly approximating the temperature increase rate at each stage as shown in FIG. In this example, the temperature increase rate that is linearly approximated in the first stage and the second stage is determined in advance, and stored in advance in the memory 42 of the control unit 4 as the temperature increase rate data 423 (FIG. 2). ). In this example, the first stage temperature rise rate is set to 0.5 ° C./second, and the second stage temperature rise rate is set to 1.0 ° C./second.

In determining the gap height position in the first stage, the temperature increase rate during the period of heating the substrate W from room temperature to 60 ° C. (preheating temperature, T1 in FIG. 9) from the temperature increase characteristic data 432. The gap height position where the average slope of is closest to 0.5 ° C./sec is selected. The time required to heat the substrate W from room temperature to 60 ° C. at this rate of temperature rise is the heating time A.
In the first stage, the thermal history V1 of the substrate W heated from room temperature (23 ° C.) to the preheating temperature (T1) is expressed by the following equation (1).
V1 = (T1-23) * A / 2 (1)

  Next, in the determination of the gap height position in the second stage, the substrate W preheated to 60 ° C. is heated to a temperature equal to or higher than the warp start temperature, and the substrate W is mounted on the heating plate 2 after the return time elapses. The heating time B is determined so as to be placed.

  That is, when the warp start temperature is lower than the preheating temperature, “the time A ′ + the time from the time when the substrate W reaches the warp start temperature in the first stage to the time when the substrate W reaches the preheat temperature + the second stage The temperature for completing the second stage is determined from the temperature increase rate of 1.0 ° C./second in the second stage so that “heating time B ≧ return time”.

  If the warpage start time is higher than the preheating temperature, the heating time required to raise the temperature of the substrate W from the preheating temperature to the warpage start temperature is B1, and after reaching the warpage start time, the second stage is performed. The temperature for completing the second stage is determined from the temperature increase rate of 1.0 ° C./second in the second stage so that “B2 ≧ return time” when the heating time until the end is B2.

  Here, as shown in FIGS. 5A and 5B, the return time of the substrate W in which the warpage has occurred becomes longer as the heating temperature of the substrate W becomes higher. However, as described with reference to FIGS. 3 and 4, the return time is the occurrence of warpage due to a sudden temperature change when the substrate W at room temperature is placed on the heating plate 2 set to each heating temperature. Later return time.

  In this regard, in the heat treatment module 1 of the present example in which the temperature is raised stepwise, the occurrence of warping is milder, and the return time varies greatly even if the temperature of the substrate W rises at each gap height position. The possibility to do is considered small. Therefore, in this example, the second stage heating time B is determined based on the return time at the warp start temperature. It should be noted that the return time under conditions where the temperature changes at the first stage or second stage temperature increase rate (0.5 ° C./sec, 1.0 ° C./sec) is obtained by preliminary experiments. Of course, the time may be stored as warpage data 431. Further, as described above, the return time described in the warp data 431 may have a margin with respect to the actual measurement result, and the influence of the temperature change may be absorbed by this margin setting range.

When the temperature T2 at which the second stage of heating is finished is determined by the method described above, the average gradient of the temperature increase rate during the period of heating the substrate W from the temperature T1 to T2 is determined from the temperature increase characteristic data 432. Select the gap height position closest to 1.0 ° C / sec. The time required to heat the substrate W from the temperature T1 to T2 at this temperature increase rate is the heating time B.
In the second stage, the thermal history V2 of the substrate W heated from the preheating temperature (T1) to the temperature T2 is expressed by the following equation (2).
V2 = (T2-T1) * B / 2 + (T1-23) * B (2)

Thereafter, the substrate W heated at the temperature T2 is placed on the heating plate 2 (third stage). At this time, the time required for the substrate W to be heated from the temperature T2 to the heating temperature T3 on the heating plate 2 is a second.
In the third stage, the thermal history V3 of the substrate W until the substrate W is raised from the heating plate 2 and the heating is finished is expressed by the following equation (3).
V3 = (T3-23) * C- (T3-T2) * a / 2 (3)

In order to align the thermal history of the substrate W shown in FIG. 9 with the conventional thermal history shown in FIG. 8, V which is the thermal history setting data 433 and the first to third stage thermal histories V1 to V3. What is necessary is just to make the sum total (Formula (4) below).
V = V1 + V2 + V3 (4)

  Therefore, in this example, the second stage heating time B and the third stage heating time C are determined so as to satisfy the condition of the expression (4). For example, from the viewpoint of shortening the processing time, the heating time B (that is, the temperature T2) in the second stage is first determined so as to be the shortest while satisfying the restriction on the return time (when T1> warp start temperature, “A “+ B = return time”, and when T1 ≦ warp start temperature, “B2 = return time”). Thereafter, the third stage heating time C is determined so as to satisfy the condition of the expression (4).

  Here, for example, as shown in the warp data 431 at a thickness of 400 μm shown in FIG. 5B, when the warp start temperature is 90 ° C. and the temperature is raised at a temperature rise rate of 1.0 ° C./sec, 30 seconds. In some cases, it is not possible to secure the return time. In addition, the selected gap height position may be smaller than the maximum displacement of the warpage amount of the substrate W.

  In this way, when the heating sequence conflicts with the restriction, an error is issued from the interface unit 5 and, for example, a change that decreases the temperature increase rate in the second stage is accepted. At this time, after increasing the number of heating stages and raising the temperature to, for example, the preheating temperature (first stage), the temperature raising rate is changed in two steps (second stage, third stage), and then You may receive the setting which mounts the board | substrate W on the heating plate 2 (4th step).

  The gap height position at each stage and the heating time determination method described above are stored in the memory 42 of the control unit 4 as the heating sequence setting program 424. For convenience of explanation, in FIG. 2, the memory 42 storing the preheating temperature data 421 and the like and the memory 43 storing the warpage data 431 and the like are shown separately, but these memories 42 and 43 are shown. Of course, they may be shared.

The operation of the heat treatment module 1 having the above-described configuration will be described with reference to FIGS.
First, an operation for creating a heating sequence for the substrate W will be described with reference to the flowchart of FIG.

  For example, at the timing of starting the processing of a new lot of substrates W (start), the substrate information (the thickness dimension of the substrate W, the presence / absence of the coating film, the thickness dimension of the coating film, the substrate material) from the operator via the interface unit 5 Etc.) and processing conditions (set temperature of the heating plate 2 and pressure conditions in the processing space) are received (step S101).

  If the substrate W does not warp at the input set temperature of the heating plate 2 (step S102; NO), a recipe for heating the substrate W directly on the heating plate 2 is created. Recipe creation data is output (step S103), and the creation operation of the heating sequence is finished (end).

  When the substrate W is warped at the input set temperature (step S102; YES), the gap height at each stage is determined from the temperature rise characteristic data 432 by the method described with reference to FIGS. The position is selected (step S104), and the heating time for each stage is determined so that the thermal history of the heating sequence to be created is aligned with the input substrate information and the thermal history setting data 433 in the processing conditions (step S105).

  Then, it is confirmed that the created heating sequence satisfies the constraints such as the return time being secured and the gap height position being larger than the maximum displacement of the warp amount (step S106). If these constraints are not satisfied (step S106; NO), an error is reported from the interface unit 5, and after changing parameters such as the temperature increase rate data 423 from the operator (step S108), the heating sequence is performed. Is repeated (steps S104 and S105).

  On the other hand, if a heating sequence that satisfies the constraints can be created (step S106; YES), the gap height and heating time at each stage are output as recipe creation data (step S107), and the creation operation of the heating sequence ends (end). .

When the heating sequence is created by the above-described operation, the substrate W is transferred to the heat treatment module 1 and heated.
First, the heat treatment module 1 stands by in a state in which the heating plate 2 is heated to a preset temperature of processing conditions set in advance. Then, for example, the resist solution is applied by the application module of the application / development apparatus, or the substrate W after the development solution is supplied and developed by the development module is transferred to the heat treatment module 1 by the substrate transfer mechanism. . At this time, as shown in FIG. 11, the heat treatment module 1 lowers the cylindrical wall portion 12 to the inside of the base portion 11, raises the support pin 3 to the delivery position, and moves from the substrate transport mechanism that has entered the heat treatment module 1. The substrate W is received.

Thereafter, the cylindrical wall portion 12 is raised to evacuate the processing space surrounded by the lid portion 13 and the cylindrical wall portion 12, and the substrate W is lowered to the gap height position in the first stage. Heat to the heating temperature (T1) (FIG. 12).
When the temperature of the substrate W is raised to the preheating temperature, the substrate W is lowered to the gap height position in the second stage, and the temperature is raised to a preset temperature (T2) (FIG. 13).

Then, when the temperature of the substrate W is raised to the temperature T2, the substrate W is placed on the heating plate 2 and heated for a time determined in the heating sequence (FIG. 14).
Thereafter, when a predetermined time elapses, the substrate W is raised to the delivery position, the exhaust in the processing space is stopped, the cylindrical wall portion 12 is lowered, and the substrate W is carried out. When it is necessary to cool the substrate W before unloading, the substrate W may be unloaded after waiting for a predetermined time at the transfer position, for example.

In these operations, as shown in FIG. 15A, warpage occurs in the process in which the substrate W transferred to the support pins 3 in a flat state is sequentially heated in the first and second stages. After that, after returning to a flat state, it is placed on the heating plate 2 and heated (FIG. 15C).
When the processing is completed, the heat treatment module 1 raises the support pins 3, lowers the cylindrical wall portion 12 and conveys it to the delivery position, and lowers the cylindrical wall portion 12. Thereafter, the substrate W is transferred to the substrate transfer mechanism that has entered the heat treatment module and transferred to the next processing module.

  The heat treatment module 1 according to the present embodiment has the following effects. After the substrate W supported by the support pins 3 is heated on the upper side of the heating plate 2 and heated to a temperature at which the substrate W is warped, a return time elapses for the warped substrate W to return flat. Then, the substrate W is placed on the heating plate 2, so that the flat substrate W can be heated uniformly. Further, after the warp is eliminated, the substrate W is placed on the heating plate 2 and heated, so that an increase in processing time can be suppressed and processing can be performed quickly.

  Here, the type of the substrate W to be heated using the heat treatment module 1 according to the present embodiment is not limited to the one using lithium tantalate as the substrate material. By performing stepwise temperature rise using the heat treatment module 1 on the substrate W composed of a substrate material selected from a substrate material group consisting of lithium tantalate, gallium arsenide, and lithium niobate, Uniform heating can be performed while suppressing the influence of warpage. When these substrate materials are viewed from the viewpoint of physical properties, if the substrate material has a thermal conductivity of 55 W / (m · ° C.) or less, the problem of warping during heating may occur. The effect of suppressing the influence of warping due to heating using 1 can be obtained.

  Further, it is not essential to exhaust the processing space in which the substrate W is heated, and the heating may be performed in an air atmosphere or an inert gas atmosphere. Further, the processing space is not limited to the example configured using the cylindrical wall portion 12 and the lid portion 13 shown in FIG. 1. For example, the heating plate 2 is provided in a housing in which a loading / unloading port for the substrate W is formed, and the loading is performed. It is good also as a structure which opens and closes an exit with a shutter.

  Furthermore, the set temperature of the heating plate 2 is not limited to the case where the temperature is raised in advance to the temperature when the substrate W is placed and processed, and the temperature of the heating plate 2 is changed in accordance with the lowering of the substrate W. May be. For example, there may be a case where the temperature of the heating plate 2 is gradually raised as the substrate W is lowered from the first stage to the third stage.

  In addition to these, the method of knowing the timing at which the return time has elapsed for the substrate W in which the warpage has occurred is not limited to the case of estimating based on the relationship between the temperature of the substrate W and the return time that have been grasped in advance. For example, warpage of the substrate W supported by the support pins 3 above the heating plate 2 may be monitored in real time with a laser displacement meter. For example, the occurrence of warpage of the substrate W can be identified by detecting the height positions at a plurality of locations on the center side and the peripheral edge side of the substrate W and obtaining the difference between these positions.

In this case, a method of slowly lowering the substrate W from the delivery position, increasing the descending speed of the substrate W at the timing when it is detected that the substrate W has returned to the flat state after the occurrence of warping, and placing the substrate W on the heating plate 2. May be adopted. Such a technique is effective for the type of substrate W in which the influence of the thermal history on the processing result is small.
As in this example, it is not essential to heat the substrate W supported by the support pins 3 at a predetermined gap height position (first and second height positions described above). The substrate W may be heated while being continuously lowered.

W Substrate 1 Heat treatment module 2 Heating plate 3 Support pin 31 Lifting member 32 Lifting motor 4 Control unit 431 Warpage data 432 Temperature rise characteristic data 433 Thermal history setting data

Claims (17)

In a heat treatment apparatus for heating a substrate,
A substrate that warps in the process of temperature rise and then returns to a flat surface is placed, a heating plate that is adjusted to a heating temperature that heats the substrate, and a projection that can be protruded from the heating plate. A support member for supporting from the lower surface side;
An elevating mechanism that is set on the upper side of the heating plate and moves the support member up and down between a delivery position where the substrate is delivered to the support member and a position on the lower side of the heating plate;
During the period in which the substrate is lowered from the delivery position, the substrate is heated up to a temperature at which warpage occurs due to the heat from the heating plate above the heating plate, and then the return time until the substrate returns to flatness is reached. And a controller that controls the position of the support member by operating the elevating mechanism so that the substrate is placed on the heating plate after the elapse of time.   The control unit stops the descent of the support member at a first height position where the substrate is heated to a temperature equal to or higher than the temperature at which the warpage occurs, the warp occurs in the substrate to be processed, and the return 2. The heat treatment apparatus according to claim 1, wherein the elevating mechanism is controlled so as to lower the support member again after a lapse of time.   The first height position is set such that a distance from the heating plate is larger than a maximum displacement in a height direction of a warp generated in the substrate at the position. The heat processing apparatus as described in.   The controller stops the lowering of the support member at a second height position above the first height position, preheats the substrate to be processed, and then moves the support member again. The heat treatment apparatus according to claim 2 or 3, wherein the elevating mechanism is controlled so as to be lowered.   The control unit estimates the timing at which the return time for the substrate to be processed elapses based on the correspondence relationship between the return time and the temperature at which the substrate warps, which is acquired in advance for each type of substrate. The heat treatment apparatus according to any one of claims 1 to 4, wherein:   The control unit obtains the temperature of the substrate to be processed based on the relationship between the distance from the heating plate adjusted to the heating temperature to the substrate, which is acquired in advance for each type of substrate, and the temporal change in the temperature of the substrate. The heat treatment apparatus according to claim 1, wherein the heat treatment apparatus is used for position control when the support member is lowered.   The control unit transfers the substrate to the support member at the delivery position, mounts the substrate on the mounting surface of the heating plate, and then lifts the substrate from the mounting surface. 7. The position and timing for raising and lowering the support member are determined based on a heating sequence set so that a time integral value of the temperature becomes a preset value. The heat processing apparatus as described in any one.   The time integral value of the temperature of the substrate is obtained on the basis of the relationship between the distance from the heating plate to the substrate and the average temperature increase rate of the substrate, obtained in advance for each type of substrate. The heat treatment apparatus according to claim 7.   9. The heat treatment apparatus according to claim 1, wherein the substrate is made of a substrate material selected from a substrate material group consisting of lithium tantalate, gallium arsenide, and lithium niobate.   The heat treatment apparatus according to claim 1, wherein the substrate is made of a substrate material having a thermal conductivity of 55 W / (m · ° C.) or less. In a heat treatment method in which a substrate is placed on a heating plate and heated,
A step of supporting a substrate on a support member provided so as to be able to project and retract with respect to the heating plate at a delivery position set on the upper side of the heating plate;
A step of raising the substrate by heat from the heating plate on the upper side of the heating plate during a period of moving the substrate by lowering the support member, and generating warpage of the substrate;
On the upper side of the heating plate, waiting for the elapse of a return time for the substrate to return to flat after the occurrence of the warpage;
And a step of lowering the support member to the lower side of the heating plate and placing the substrate on the heating plate after the return time has elapsed.   The step of causing the substrate to warp and the step of waiting for the elapse of the return time stop the lowering of the support member at a first height position where the substrate is heated to a temperature equal to or higher than the temperature at which the warp occurs. The heat treatment method according to claim 11, wherein the heat treatment method is performed.   The first height position is set to a position where a distance from the heating plate is larger than a maximum displacement in a height direction of a warp generated in the substrate at the position. A heat treatment method according to 1.   Stopping the lowering of the support member at a second height position above the first height position, preheating the substrate to be processed, and then lowering the support member again. The heat treatment method according to claim 12 or 13, characterized in that:   15. The heat treatment method according to claim 11, wherein the substrate is made of a substrate material selected from a substrate material group consisting of lithium tantalate, gallium arsenide, and lithium niobate.   The heat treatment method according to claim 11, wherein the substrate is made of a substrate material having a thermal conductivity of 55 W / (m · ° C.) or less. A storage medium for storing a computer program used in a heat treatment apparatus provided with a heating plate for heating a mounted substrate,
A storage medium in which the computer program includes a set of steps so as to execute the heat treatment method according to any one of claims 11 to 16.

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